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Ganeti installation tutorial |
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============================ |
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Documents Ganeti version |version| |
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.. contents:: |
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.. highlight:: text |
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Introduction |
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------------ |
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|
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Ganeti is a cluster virtualization management system based on Xen or |
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KVM. This document explains how to bootstrap a Ganeti node (Xen *dom0*, |
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the host Linux system for KVM), create a running cluster and install |
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virtual instances (Xen *domUs*, KVM guests). You need to repeat most of |
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the steps in this document for every node you want to install, but of |
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course we recommend creating some semi-automatic procedure if you plan |
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to deploy Ganeti on a medium/large scale. |
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|
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A basic Ganeti terminology glossary is provided in the introductory |
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section of the :doc:`admin`. Please refer to that document if you are |
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uncertain about the terms we are using. |
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|
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Ganeti has been developed for Linux and should be distribution-agnostic. |
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This documentation will use Debian Lenny as an example system but the |
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examples can be translated to any other distribution. You are expected |
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to be familiar with your distribution, its package management system, |
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and Xen or KVM before trying to use Ganeti. |
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|
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This document is divided into two main sections: |
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|
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- Installation of the base system and base components |
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|
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- Configuration of the environment for Ganeti |
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|
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Each of these is divided into sub-sections. While a full Ganeti system |
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will need all of the steps specified, some are not strictly required for |
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every environment. Which ones they are, and why, is specified in the |
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corresponding sections. |
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|
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Installing the base system and base components |
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---------------------------------------------- |
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|
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Hardware requirements |
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+++++++++++++++++++++ |
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|
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Any system supported by your Linux distribution is fine. 64-bit systems |
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are better as they can support more memory. |
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|
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Any disk drive recognized by Linux (``IDE``/``SCSI``/``SATA``/etc.) is |
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supported in Ganeti. Note that no shared storage (e.g. ``SAN``) is |
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needed to get high-availability features (but of course, one can be used |
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to store the images). It is highly recommended to use more than one disk |
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drive to improve speed. But Ganeti also works with one disk per machine. |
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|
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Installing the base system |
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++++++++++++++++++++++++++ |
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|
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**Mandatory** on all nodes. |
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|
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It is advised to start with a clean, minimal install of the operating |
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system. The only requirement you need to be aware of at this stage is to |
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partition leaving enough space for a big (**minimum** 20GiB) LVM volume |
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group which will then host your instance filesystems, if you want to use |
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all Ganeti features. The volume group name Ganeti uses (by default) is |
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``xenvg``. |
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|
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You can also use file-based storage only, without LVM, but this setup is |
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not detailed in this document. |
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|
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While you can use an existing system, please note that the Ganeti |
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installation is intrusive in terms of changes to the system |
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configuration, and it's best to use a newly-installed system without |
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important data on it. |
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|
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Also, for best results, it's advised that the nodes have as much as |
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possible the same hardware and software configuration. This will make |
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administration much easier. |
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|
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Hostname issues |
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~~~~~~~~~~~~~~~ |
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|
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Note that Ganeti requires the hostnames of the systems (i.e. what the |
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``hostname`` command outputs to be a fully-qualified name, not a short |
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name. In other words, you should use *node1.example.com* as a hostname |
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and not just *node1*. |
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|
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.. admonition:: Debian |
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|
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Debian Lenny and Etch configures the hostname differently than you |
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need it for Ganeti. For example, this is what Etch puts in |
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``/etc/hosts`` in certain situations:: |
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|
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127.0.0.1 localhost |
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127.0.1.1 node1.example.com node1 |
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|
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but for Ganeti you need to have:: |
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|
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127.0.0.1 localhost |
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192.168.1.1 node1.example.com node1 |
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|
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replacing ``192.168.1.1`` with your node's address. Also, the file |
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``/etc/hostname`` which configures the hostname of the system |
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should contain ``node1.example.com`` and not just ``node1`` (you |
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need to run the command ``/etc/init.d/hostname.sh start`` after |
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changing the file). |
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|
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.. admonition:: Why a fully qualified host name |
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|
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Although most distributions use only the short name in the |
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/etc/hostname file, we still think Ganeti nodes should use the full |
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name. The reason for this is that calling 'hostname --fqdn' requires |
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the resolver library to work and is a 'guess' via heuristics at what |
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is your domain name. Since Ganeti can be used among other things to |
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host DNS servers, we don't want to depend on them as much as |
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possible, and we'd rather have the uname() syscall return the full |
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node name. |
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|
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We haven't ever found any breakage in using a full hostname on a |
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Linux system, and anyway we recommend to have only a minimal |
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installation on Ganeti nodes, and to use instances (or other |
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dedicated machines) to run the rest of your network services. By |
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doing this you can change the /etc/hostname file to contain an FQDN |
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without the fear of breaking anything unrelated. |
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|
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|
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Installing The Hypervisor |
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+++++++++++++++++++++++++ |
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|
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**Mandatory** on all nodes. |
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|
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While Ganeti is developed with the ability to modularly run on different |
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virtualization environments in mind the only two currently useable on a |
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live system are Xen and KVM. Supported Xen versions are: 3.0.3, 3.0.4 |
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and 3.1. Supported KVM version are 72 and above. |
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|
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Please follow your distribution's recommended way to install and set up |
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Xen, or install Xen from the upstream source, if you wish, following |
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their manual. For KVM, make sure you have a KVM-enabled kernel and the |
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KVM tools. |
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|
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After installing Xen, you need to reboot into your new system. On some |
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distributions this might involve configuring GRUB appropriately, whereas |
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others will configure it automatically when you install the respective |
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kernels. For KVM no reboot should be necessary. |
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|
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.. admonition:: Xen on Debian |
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Under Lenny or Etch you can install the relevant ``xen-linux-system`` |
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package, which will pull in both the hypervisor and the relevant |
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kernel. Also, if you are installing a 32-bit Lenny/Etch, you should |
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install the ``libc6-xen`` package (run ``apt-get install |
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libc6-xen``). |
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|
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Xen settings |
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~~~~~~~~~~~~ |
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|
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It's recommended that dom0 is restricted to a low amount of memory |
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(512MiB or 1GiB is reasonable) and that memory ballooning is disabled in |
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the file ``/etc/xen/xend-config.sxp`` by setting the value |
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``dom0-min-mem`` to 0, like this:: |
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|
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(dom0-min-mem 0) |
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|
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For optimum performance when running both CPU and I/O intensive |
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instances, it's also recommended that the dom0 is restricted to one CPU |
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only, for example by booting with the kernel parameter ``nosmp``. |
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|
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It is recommended that you disable xen's automatic save of virtual |
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machines at system shutdown and subsequent restore of them at reboot. |
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To obtain this make sure the variable ``XENDOMAINS_SAVE`` in the file |
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``/etc/default/xendomains`` is set to an empty value. |
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|
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If you want to use live migration make sure you have, in the xen config |
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file, something that allows the nodes to migrate instances between each |
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other. For example:: |
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|
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(xend-relocation-server yes) |
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(xend-relocation-port 8002) |
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(xend-relocation-address '') |
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(xend-relocation-hosts-allow '^192\\.168\\.3\\.[0-9]+$') |
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|
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|
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The second line assumess that the hypervisor parameter |
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``migration_port`` is set 8002, otherwise modify it to match. The last |
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line assumes that all your nodes have secondary IPs in the |
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192.168.3.0/24 network, adjust it accordingly to your setup. |
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|
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.. admonition:: Debian |
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|
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Besides the ballooning change which you need to set in |
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``/etc/xen/xend-config.sxp``, you need to set the memory and nosmp |
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parameters in the file ``/boot/grub/menu.lst``. You need to modify |
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the variable ``xenhopt`` to add ``dom0_mem=1024M`` like this:: |
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|
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## Xen hypervisor options to use with the default Xen boot option |
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# xenhopt=dom0_mem=1024M |
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|
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and the ``xenkopt`` needs to include the ``nosmp`` option like this:: |
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## Xen Linux kernel options to use with the default Xen boot option |
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# xenkopt=nosmp |
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|
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Any existing parameters can be left in place: it's ok to have |
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``xenkopt=console=tty0 nosmp``, for example. After modifying the |
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files, you need to run:: |
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|
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/sbin/update-grub |
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|
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If you want to run HVM instances too with Ganeti and want VNC access to |
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the console of your instances, set the following two entries in |
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``/etc/xen/xend-config.sxp``:: |
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(vnc-listen '0.0.0.0') (vncpasswd '') |
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You need to restart the Xen daemon for these settings to take effect:: |
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/etc/init.d/xend restart |
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Selecting the instance kernel |
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
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|
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After you have installed Xen, you need to tell Ganeti exactly what |
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kernel to use for the instances it will create. This is done by creating |
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a symlink from your actual kernel to ``/boot/vmlinuz-2.6-xenU``, and one |
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from your initrd to ``/boot/initrd-2.6-xenU`` [#defkernel]_. Note that |
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if you don't use an initrd for the domU kernel, you don't need to create |
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the initrd symlink. |
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|
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.. admonition:: Debian |
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|
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After installation of the ``xen-linux-system`` package, you need to |
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run (replace the exact version number with the one you have):: |
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cd /boot |
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ln -s vmlinuz-2.6.26-1-xen-amd64 vmlinuz-2.6-xenU |
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ln -s initrd.img-2.6.26-1-xen-amd64 initrd-2.6-xenU |
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|
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Installing DRBD |
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+++++++++++++++ |
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|
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Recommended on all nodes: DRBD_ is required if you want to use the high |
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availability (HA) features of Ganeti, but optional if you don't require |
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them or only run Ganeti on single-node clusters. You can upgrade a |
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non-HA cluster to an HA one later, but you might need to export and |
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re-import all your instances to take advantage of the new features. |
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|
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.. _DRBD: http://www.drbd.org/ |
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|
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Supported DRBD versions: 8.0+. It's recommended to have at least version |
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8.0.12. Note that for version 8.2 and newer it is needed to pass the |
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``usermode_helper=/bin/true`` parameter to the module, either by |
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configuring ``/etc/modules`` or when inserting it manually. |
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|
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Now the bad news: unless your distribution already provides it |
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installing DRBD might involve recompiling your kernel or anyway fiddling |
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with it. Hopefully at least the Xen-ified kernel source to start from |
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will be provided (if you intend to use Xen). |
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|
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The good news is that you don't need to configure DRBD at all. Ganeti |
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will do it for you for every instance you set up. If you have the DRBD |
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utils installed and the module in your kernel you're fine. Please check |
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that your system is configured to load the module at every boot, and |
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that it passes the following option to the module: |
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``minor_count=NUMBER``. We recommend that you use 128 as the value of |
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the minor_count - this will allow you to use up to 64 instances in total |
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per node (both primary and secondary, when using only one disk per |
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instance). You can increase the number up to 255 if you need more |
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instances on a node. |
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|
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|
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.. admonition:: Debian |
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|
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On Debian, you can just install (build) the DRBD module with the |
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following commands, making sure you are running the target (Xen or |
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KVM) kernel:: |
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|
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apt-get install drbd8-source drbd8-utils |
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m-a update |
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m-a a-i drbd8 |
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echo drbd minor_count=128 usermode_helper=/bin/true >> /etc/modules |
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depmod -a |
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modprobe drbd minor_count=128 usermode_helper=/bin/true |
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|
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It is also recommended that you comment out the default resources in |
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the ``/etc/drbd.conf`` file, so that the init script doesn't try to |
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configure any drbd devices. You can do this by prefixing all |
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*resource* lines in the file with the keyword *skip*, like this:: |
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|
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skip resource r0 { |
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... |
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} |
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|
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skip resource "r1" { |
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... |
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} |
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|
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Other required software |
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+++++++++++++++++++++++ |
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|
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See :doc:`install-quick`. |
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|
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Setting up the environment for Ganeti |
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------------------------------------- |
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|
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Configuring the network |
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+++++++++++++++++++++++ |
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|
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**Mandatory** on all nodes. |
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|
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You can run Ganeti either in "bridge mode" or in "routed mode". In |
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bridge mode, the default, the instances network interfaces will be |
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attached to a software bridge running in dom0. Xen by default creates |
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such a bridge at startup, but your distribution might have a different |
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way to do things, and you'll definitely need to manually set it up under |
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KVM. |
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|
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Beware that the default name Ganeti uses is ``xen-br0`` (which was used |
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in Xen 2.0) while Xen 3.0 uses ``xenbr0`` by default. See the |
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`Initializing the cluster`_ section to learn how to choose a different |
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bridge, or not to use one at all and use "routed mode". |
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|
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In order to use "routed mode" under Xen, you'll need to change the |
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relevant parameters in the Xen config file. Under KVM instead, no config |
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change is necessary, but you still need to set up your network |
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interfaces correctly. |
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|
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By default, under KVM, the "link" parameter you specify per-nic will |
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represent, if non-empty, a different routing table name or number to use |
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for your instances. This allows insulation between different instance |
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groups, and different routing policies between node traffic and instance |
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traffic. |
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|
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You will need to configure your routing table basic routes and rules |
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outside of ganeti. The vif scripts will only add /32 routes to your |
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instances, through their interface, in the table you specified (under |
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KVM, and in the main table under Xen). |
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|
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.. admonition:: Bridging under Debian |
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|
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The recommended way to configure the Xen bridge is to edit your |
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``/etc/network/interfaces`` file and substitute your normal |
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Ethernet stanza with the following snippet:: |
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|
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auto xen-br0 |
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iface xen-br0 inet static |
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address YOUR_IP_ADDRESS |
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netmask YOUR_NETMASK |
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network YOUR_NETWORK |
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broadcast YOUR_BROADCAST_ADDRESS |
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gateway YOUR_GATEWAY |
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bridge_ports eth0 |
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bridge_stp off |
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bridge_fd 0 |
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|
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The following commands need to be executed on the local console: |
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|
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ifdown eth0 |
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ifup xen-br0 |
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|
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To check if the bridge is setup, use the ``ip`` and ``brctl show`` |
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commands:: |
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|
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# ip a show xen-br0 |
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9: xen-br0: <BROADCAST,MULTICAST,UP,10000> mtu 1500 qdisc noqueue |
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link/ether 00:20:fc:1e:d5:5d brd ff:ff:ff:ff:ff:ff |
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inet 10.1.1.200/24 brd 10.1.1.255 scope global xen-br0 |
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inet6 fe80::220:fcff:fe1e:d55d/64 scope link |
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valid_lft forever preferred_lft forever |
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|
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# brctl show xen-br0 |
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bridge name bridge id STP enabled interfaces |
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xen-br0 8000.0020fc1ed55d no eth0 |
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|
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.. _configure-lvm-label: |
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|
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Configuring LVM |
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+++++++++++++++ |
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|
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**Mandatory** on all nodes. |
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|
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The volume group is required to be at least 20GiB. |
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|
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If you haven't configured your LVM volume group at install time you need |
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to do it before trying to initialize the Ganeti cluster. This is done by |
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formatting the devices/partitions you want to use for it and then adding |
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them to the relevant volume group:: |
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|
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pvcreate /dev/sda3 |
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vgcreate xenvg /dev/sda3 |
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|
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or:: |
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|
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pvcreate /dev/sdb1 |
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pvcreate /dev/sdc1 |
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vgcreate xenvg /dev/sdb1 /dev/sdc1 |
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|
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If you want to add a device later you can do so with the *vgextend* |
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command:: |
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|
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pvcreate /dev/sdd1 |
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vgextend xenvg /dev/sdd1 |
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|
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Optional: it is recommended to configure LVM not to scan the DRBD |
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devices for physical volumes. This can be accomplished by editing |
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``/etc/lvm/lvm.conf`` and adding the ``/dev/drbd[0-9]+`` regular |
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expression to the ``filter`` variable, like this:: |
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|
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filter = ["r|/dev/cdrom|", "r|/dev/drbd[0-9]+|" ] |
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|
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Note that with Ganeti a helper script is provided - ``lvmstrap`` which |
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will erase and configure as LVM any not in-use disk on your system. This |
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is dangerous and it's recommended to read its ``--help`` output if you |
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want to use it. |
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|
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Installing Ganeti |
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+++++++++++++++++ |
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|
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**Mandatory** on all nodes. |
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|
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It's now time to install the Ganeti software itself. Download the |
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source from the project page at `<http://code.google.com/p/ganeti/>`_, |
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and install it (replace 2.0.0 with the latest version):: |
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|
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tar xvzf ganeti-2.0.0.tar.gz |
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cd ganeti-2.0.0 |
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./configure --localstatedir=/var --sysconfdir=/etc |
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make |
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make install |
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mkdir /srv/ganeti/ /srv/ganeti/os /srv/ganeti/export |
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|
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You also need to copy the file ``doc/examples/ganeti.initd`` from the |
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source archive to ``/etc/init.d/ganeti`` and register it with your |
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distribution's startup scripts, for example in Debian:: |
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|
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update-rc.d ganeti defaults 20 80 |
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|
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In order to automatically restart failed instances, you need to setup a |
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cron job run the *ganeti-watcher* command. A sample cron file is |
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provided in the source at ``doc/examples/ganeti.cron`` and you can copy |
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that (eventually altering the path) to ``/etc/cron.d/ganeti``. |
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|
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What gets installed |
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~~~~~~~~~~~~~~~~~~~ |
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|
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The above ``make install`` invocation, or installing via your |
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distribution mechanisms, will install on the system: |
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|
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- a set of python libraries under the *ganeti* namespace (depending on |
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the python version this can be located in either |
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``lib/python-$ver/site-packages`` or various other locations) |
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- a set of programs under ``/usr/local/sbin`` or ``/usr/sbin`` |
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- man pages for the above programs |
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- a set of tools under the ``lib/ganeti/tools`` directory |
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- an example iallocator script (see the admin guide for details) under |
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``lib/ganeti/iallocators`` |
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- a cron job that is needed for cluster maintenance |
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- an init script for automatic startup of Ganeti daemons |
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- provided but not installed automatically by ``make install`` is a bash |
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completion script that hopefully will ease working with the many |
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cluster commands |
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|
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Installing the Operating System support packages |
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++++++++++++++++++++++++++++++++++++++++++++++++ |
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|
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**Mandatory** on all nodes. |
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|
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To be able to install instances you need to have an Operating System |
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installation script. An example OS that works under Debian and can |
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install Debian and Ubuntu instace OSes is provided on the project web |
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site. Download it from the project page and follow the instructions in |
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the ``README`` file. Here is the installation procedure (replace 0.9 |
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with the latest version that is compatible with your ganeti version):: |
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|
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cd /usr/local/src/ |
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wget http://ganeti.googlecode.com/files/ganeti-instance-debootstrap-0.9.tar.gz |
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tar xzf ganeti-instance-debootstrap-0.9.tar.gz |
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cd ganeti-instance-debootstrap-0.9 |
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./configure |
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make |
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make install |
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|
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In order to use this OS definition, you need to have internet access |
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from your nodes and have the *debootstrap*, *dump* and *restore* |
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commands installed on all nodes. Also, if the OS is configured to |
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partition the instance's disk in |
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``/etc/default/ganeti-instance-debootstrap``, you will need *kpartx* |
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installed. |
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|
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.. admonition:: Debian |
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|
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Use this command on all nodes to install the required packages:: |
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|
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apt-get install debootstrap dump kpartx |
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|
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.. admonition:: KVM |
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|
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In order for debootstrap instances to be able to shutdown cleanly |
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they must install have basic acpi support inside the instance. Which |
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packages are needed depend on the exact flavor of debian or ubuntu |
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which you're installing, but the example defaults file has a |
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commented out configuration line that works for debian lenny and |
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squeeze:: |
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|
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EXTRA_PKGS="acpi-support-base,console-tools,udev" |
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|
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kbd can be used instead of console-tools, and more packages can be |
509 |
added, of course, if needed. |
510 |
|
511 |
Alternatively, you can create your own OS definitions. See the manpage |
512 |
:manpage:`ganeti-os-interface`. |
513 |
|
514 |
Initializing the cluster |
515 |
++++++++++++++++++++++++ |
516 |
|
517 |
**Mandatory** once per cluster, on the first node. |
518 |
|
519 |
The last step is to initialize the cluster. After you have repeated the |
520 |
above process on all of your nodes, choose one as the master, and |
521 |
execute:: |
522 |
|
523 |
gnt-cluster init <CLUSTERNAME> |
524 |
|
525 |
The *CLUSTERNAME* is a hostname, which must be resolvable (e.g. it must |
526 |
exist in DNS or in ``/etc/hosts``) by all the nodes in the cluster. You |
527 |
must choose a name different from any of the nodes names for a |
528 |
multi-node cluster. In general the best choice is to have a unique name |
529 |
for a cluster, even if it consists of only one machine, as you will be |
530 |
able to expand it later without any problems. Please note that the |
531 |
hostname used for this must resolve to an IP address reserved |
532 |
**exclusively** for this purpose, and cannot be the name of the first |
533 |
(master) node. |
534 |
|
535 |
If you want to use a bridge which is not ``xen-br0``, or no bridge at |
536 |
all, change it with the ``--nic-parameters`` option. For example to |
537 |
bridge on br0 you can say:: |
538 |
|
539 |
--nic-parameters link=br0 |
540 |
|
541 |
Or to not bridge at all, and use a separate routing table:: |
542 |
|
543 |
--nic-parameters mode=routed,link=100 |
544 |
|
545 |
If you don't have a xen-br0 interface you also have to specify a |
546 |
different network interface which will get the cluster ip, on the master |
547 |
node, by using the ``--master-netdev <device>`` option. |
548 |
|
549 |
You can use a different name than ``xenvg`` for the volume group (but |
550 |
note that the name must be identical on all nodes). In this case you |
551 |
need to specify it by passing the *-g <VGNAME>* option to ``gnt-cluster |
552 |
init``. |
553 |
|
554 |
To set up the cluster as an Xen HVM cluster, use the |
555 |
``--enabled-hypervisors=xen-hvm`` option to enable the HVM hypervisor |
556 |
(you can also add ``,xen-pvm`` to enable the PVM one too). You will also |
557 |
need to create the VNC cluster password file |
558 |
``/etc/ganeti/vnc-cluster-password`` which contains one line with the |
559 |
default VNC password for the cluster. |
560 |
|
561 |
To setup the cluster for KVM-only usage (KVM and Xen cannot be mixed), |
562 |
pass ``--enabled-hypervisors=kvm`` to the init command. |
563 |
|
564 |
You can also invoke the command with the ``--help`` option in order to |
565 |
see all the possibilities. |
566 |
|
567 |
Hypervisor/Network/Cluster parameters |
568 |
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
569 |
|
570 |
Please note that the default hypervisor/network/cluster parameters may |
571 |
not be the correct one for your environment. Carefully check them, and |
572 |
change them at cluster init time, or later with ``gnt-cluster modify``. |
573 |
|
574 |
Your instance types, networking environment, hypervisor type and version |
575 |
may all affect what kind of parameters should be used on your cluster. |
576 |
|
577 |
For example kvm instances are by default configured to use a host |
578 |
kernel, and to be reached via serial console, which works nice for linux |
579 |
paravirtualized instances. If you want fully virtualized instances you |
580 |
may want to handle their kernel inside the instance, and to use VNC. |
581 |
|
582 |
Joining the nodes to the cluster |
583 |
++++++++++++++++++++++++++++++++ |
584 |
|
585 |
**Mandatory** for all the other nodes. |
586 |
|
587 |
After you have initialized your cluster you need to join the other nodes |
588 |
to it. You can do so by executing the following command on the master |
589 |
node:: |
590 |
|
591 |
gnt-node add <NODENAME> |
592 |
|
593 |
Separate replication network |
594 |
++++++++++++++++++++++++++++ |
595 |
|
596 |
**Optional** |
597 |
|
598 |
Ganeti uses DRBD to mirror the disk of the virtual instances between |
599 |
nodes. To use a dedicated network interface for this (in order to |
600 |
improve performance or to enhance security) you need to configure an |
601 |
additional interface for each node. Use the *-s* option with |
602 |
``gnt-cluster init`` and ``gnt-node add`` to specify the IP address of |
603 |
this secondary interface to use for each node. Note that if you |
604 |
specified this option at cluster setup time, you must afterwards use it |
605 |
for every node add operation. |
606 |
|
607 |
Testing the setup |
608 |
+++++++++++++++++ |
609 |
|
610 |
Execute the ``gnt-node list`` command to see all nodes in the cluster:: |
611 |
|
612 |
# gnt-node list |
613 |
Node DTotal DFree MTotal MNode MFree Pinst Sinst |
614 |
node1.example.com 197404 197404 2047 1896 125 0 0 |
615 |
|
616 |
The above shows a couple of things: |
617 |
|
618 |
- The various Ganeti daemons can talk to each other |
619 |
- Ganeti can examine the storage of the node (DTotal/DFree) |
620 |
- Ganeti can talk to the selected hypervisor (MTotal/MNode/MFree) |
621 |
|
622 |
Cluster burnin |
623 |
~~~~~~~~~~~~~~ |
624 |
|
625 |
With Ganeti a tool called :command:`burnin` is provided that can test |
626 |
most of the Ganeti functionality. The tool is installed under the |
627 |
``lib/ganeti/tools`` directory (either under ``/usr`` or ``/usr/local`` |
628 |
based on the installation method). See more details under |
629 |
:ref:`burnin-label`. |
630 |
|
631 |
Further steps |
632 |
------------- |
633 |
|
634 |
You can now proceed either to the :doc:`admin`, or read the manpages of |
635 |
the various commands (:manpage:`ganeti(7)`, :manpage:`gnt-cluster(8)`, |
636 |
:manpage:`gnt-node(8)`, :manpage:`gnt-instance(8)`, |
637 |
:manpage:`gnt-job(8)`). |
638 |
|
639 |
.. rubric:: Footnotes |
640 |
|
641 |
.. [#defkernel] The kernel and initrd paths can be changed at either |
642 |
cluster level (which changes the default for all instances) or at |
643 |
instance level. |
644 |
|
645 |
.. vim: set textwidth=72 : |
646 |
.. Local Variables: |
647 |
.. mode: rst |
648 |
.. fill-column: 72 |
649 |
.. End: |